Light emitting device package and light unit having the same

ABSTRACT

Discussed is an LED package The LED package includes a body having a cavity at one side thereof, at least one of lead frames having a bottom frame and a sidewall frame in the cavity, and a light emitting device electrically connected with the lead frames.

This application is a Continuation of application Ser. No. 12/530,637filed on Sep. 10, 2009, now U.S. Pat. No. 7,858,993, which is thenational phase of PCT International Application No. PCT/KR2008/002183filed on Apr. 17, 2008, and which claims priority to Application No.10-2007-0038279 filed in the Republic of Korea on Apr. 19, 2007. Theentire contents of all of the above applications is hereby incorporatedby reference.

TECHNICAL FIELD

The embodiment relates to an LED (light emitting device) package and alight unit having the same.

BACKGROUND ART

An LED constitutes a light emission source by using GaAs, AlGaAs, GaN,InGaN and InGaAlP-based compound semiconductor materials, therebyproducing various colors.

Such characteristics of the LED can be determined by materials, colon,brightness and a brightness range of a compound semiconductor. Further,the LED is provided as a package and is applied to various fieldscomprising lighting indicators for displaying colors, characterindicators, image indicators and the like.

DISCLOSURE OF INVENTION Technical Problem

The embodiment provides an LED package, in which a lead frame bent in amulti-step is disposed at a bottom surface and at least one sidewalldefining a cavity, and a light unit having the same.

The embodiment provides an LED package, in which at least one of plurallead frames is formed at a bottom surface and both sidewalls defining acavity, and a light unit having the same.

The embodiment provides an LED package comprising a lead frame, whichhas sidewalls inclined at a predetermined angle or bent with apredetermined curvature, and a light unit having the same.

Technical Solution

An embodiment provides an LED package comprising; a body comprising acavity at one side thereof; at least one of lead frames comprising abottom frame and a sidewall frame in the cavity; and a light emittingdevice electrically connected with the lead frames.

An embodiment provides an LED package comprising; a body comprising acavity; a fast lead frame comprising a bottom frame and at least onesidewall frame at a fast side of the cavity; a second lead framecomprising a bottom frame at a second side of the cavity; and a lightemitting device electrically connected with the first and second leadframes.

An embodiment provides a light unit comprising; a light emittingapparatus comprising a plurality of LED packages; an optical guide platedisposed at one side of the light emitting device; and an optical memberdisposed above and/or below the optical guide plate, wherein the LEDpackage comprises a body comprising a cavity; at least one of leadframes comprising bottom frame and a sidewall frame in the cavity; and alight emitting device electrically connected with the lead frames.

Advantageous Effects

The embodiment can reduce optical loss in a cavity of an LED package.

The embodiment can improve the light intensity at a center area in acavity of an LED package.

The embodiment can increase the amount of reflected light in a cavity ofan LED package by using a lead frame plated with reflective metal orreflective material.

The embodiment can improve thermal resistance and thermalcharacteristics of a lead frame of an LED package.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing an LED package according to anembodiment;

FIG. 2 is a sectional view taken along an X axis of an LED package shownin FIG. 1;

FIG. 3 is a perspective view showing the lead frame of FIG. 1

FIG. 4 is a sectional view taken along a Y axis of the LED package shownin FIG. 1;

FIG. 5 is a sectional view showing an LED package having a lead framemodified according to a first example embodiment;

FIG. 6 is a sectional view showing an LED package having a lead framemodified according to a second example embodiment;

FIGS. 7 to 10 are views showing lead frames modified according to thirdto sixth example embodiments;

FIG. 11 is a graph showing an angle of a lead frame as a function oflight intensity before and after the plating in the LED package of FIG.4;

FIG. 12 is a graph showing an angle of a lead frame as a function oflight velocity (or light amount) before and after the plating in the LEDpackage of FIG. 4; and

FIG. 13 is a perspective view showing a display device using the LEDpackage of FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an LED package according to an embodiment will be describedwith reference to the accompanying drawings.

FIG. 1 is a front view showing an LED package according to a firstembodiment, FIG. 2 is a sectional view taken along an X axis of the LEDpackage shown in FIG. 1, and FIG. 3 is a perspective view showing thelead frame of FIG. 1.

Referring to FIGS. 1 and 2, the LED package 100 comprises a polygonalshape, such as a rectangular parallelepiped shape or a regularhexahedral shape, and is classified into a side emission type LEDpackage and a top emission type LED package. Further, the LED package100 can be used as a light source for a backlight unit of an LCD or as alight unit in an illumination field. Hereinafter, a side emission typeLED package will be described for convenience of decryption.

The LED package comprises a body 110 comprising a cavity 120, leadframes 130 and 140, and a light emitting device 150.

The body 110 comprises one selected from the group consisting of PPA(polyphthalamid), PA9T (polyamid9T), liquid crystal polymer and SPS(syndiotactic polystyrene).

The body 110 is formed therein with the cavity 120 comprising apredetermined depth. When a first direction is referred to as an X axisand a second direction is referred to as a Y axis, the length of thebody 110 in the X axis direction may be greater than the width of thebody 110 in the Y axis direction. However, the scope of the presentinvention is not limited thereto.

The lead frames 130 and 140 are formed at the upper portion of the body110 through injection molding. A part of the lead frames 130 and 140 isexposed to the cavity 120 of the body 110.

Referring to FIGS. 1 to 3, the lead frames 130 and 140 comprises bottomframes 131 and 141 and sidewall frames 132 and 142 in the cavity 120,respectively. One end of the bottom frame 131 and one end of the bottomframe 141 may serve as external electrodes 133 and 143 by passingthrough the body 110 in the X axis direction, respectively. The sidewallframes 132 and 142 are inclined outward from the Y axis, which isperpendicular to the bottom frames 131 and 141, at a predeterminedangle. The external electrodes 133 and 143 can be provided by one of thebottom frames 131 and 141 and the sidewall frames 132 and 142.

The lead frames 130 and 140 are formed through injection molding usinghigh reflective metals comprising one selected from the group consistingof Fe, Sn, Cr, Zn, Ni, Al, Ag, Au, Cu, and an alloy thereof.

One of the lead frames 130 and 140, for instance, the lead frame 130 mayhave a substantially “C” shape in which three sides are bent at apredetermined angle, and the other one of the lead frames 130 and 140,for instance, the lead frame 140 may form the bottom frame 141. Further,at least one of the lead frames 130 and 140, for instance, the leadframe 130 can comprise the bottom frame 131 and at least one of thesidewall frames 132. According to the embodiment, the lead frames 130and 140 may have shapes different from each other. However, the scope ofthe present invention is not limited thereto.

The lead frames 130 and 140 are integrally formed in the cavity 120 andmay have lengths different from each other. Further, the lead frames 130and 140 can be formed with a thickness of 20 μm to 300 μm.

A partition 125 serving as a part of the body 110 is formed between thelead frames 130 and 140 to structurally separate the lead frame 130 fromthe lead frame 140. Thus, the lead frames 130 and 140 serve aselectrodes and reflect light.

Both sides (i.e. left and right sides 121 and 122) defining the cavity120 in the X direction are inclined at a predetermined angle and serveas a part of the body 110. The partition 125 and the left and rightsides 121 and 122, which are disposed in the cavity 120, can be formedtogether with the cavity 120 when the body 110 is formed.

The light emitting device 150 is attached to at least one of the leadframes 130 and 140 in the cavity 120, and is connected with the leadframes 130 and 140 through a wire 152. The light emitting device 150 canbe mounted on the lead frames 130 and 140 through wire bonding, flipbonding, die bonding and the like.

Further, the light emitting device 150 is a III-V group compoundsemiconductor and comprises one of AlGaN, GaN, InGaAlP and GaAs-basedLED chips. Further, a protective device such as a Zener diode can bemounted on the lead frames 130 and 140 in order to protect the lightemitting device 150.

Meanwhile, the LED package 100 can be prepared in the form of a whitelight emitting device using a blue LED chip and a yellow fluorescentsubstance (e.g. silicate-based fluorescent substance), orangefluorescent substance, green fluorescent substance, and red fluorescentsubstance. Further, the LED package 100 can be prepared in the form of alight source by combining at least one of a red LED chip, a green LEDchip, a blue LED chip, a yellow LED chip, a yellow green LED chip and anUV LED chip.

In addition, a resin member (not shown) can be molded in the cavity 120in order to protect the light emitting device 150. The resin member canuse epoxy or silicon having transparent material. If the situationrequires, fluorescent substance powder can also be added to the resinmember and molded in the cavity 120. Molding solution or additive can beused with the resin member according to the use purpose and environment,and the characteristics of a product. However, the embodiment is notlimited thereto. Further, the surface of the resin member has one of aflat shape, a concave lens shape and a convex lens shape.

FIG. 4 is a sectional view taken along a Y axis of the LED package shownin FIG. 1. Hereinafter, the lead frame 130 of the lead frames 130 and140 will be described as an example. However, it should be noted thatthe lead frames may not be formed under the same conditions as will bedescribed later.

Referring to FIG. 4, the body 110 has a predetermined height H1, e.g.maximum 1 mm. For instance, the sidewall frames 132 of the lead frame130 has an internal angle θ1 of 30° Further, the sidewall frames 132 canbe inclined at the same angle (e.g. 15°) or at different angles withrespect to the axis perpendicular to the bottom frame 131 of the leadframe 130.

The interval D1 between the sidewall frames 132 may vary according tothe internal angle θ1 between the sidewall frames 132 of the lead frame130. For instance, the bottom frame 131 of the lead frame 130 has awidth W1 of 300 μm to 310 μm.

FIG. 5 is a sectional view showing the LED package comprising a leadframe modified according to a first example embodiment. In describingthe above first example embodiment about the lead frame, the samereference numerals are used to designate the same elements of FIG. 4,and a detailed description will be omitted in order to avoid redundancy.

Referring FIG. 5, the height H2 of the body 110 and the width W2 of thebottom frame 131 may be identical to or different from those of FIG. 4,respectively. For instance, an internal angle θ2 between the sidewallframes 132 of a lead frame 130A is 45° Each sidewall frame 132 can beinclined at an angle of 22.5° with respect to the axis perpendicular tothe bottom frame 131. As the internal angle θ2 between the sidewallframes 132 of the lead frame 130A is increased, an interval D2 (D2>D1)between the sidewall frames 132 can be further widened. The interval D2between the sidewall frames 132 is widened, so that the surface width ofthe cavity 120 can be increased.

FIG. 6 is a sectional view showing the LED package comprising a leadframe modified according to a second example embodiment. In describingthe second example embodiment about the lead frame, the same referencenumerals are used to designate the same elements of FIG. 4, and adetailed description will be omitted in order to avoid redundancy.

Referring to FIG. 6, the height H1 of the body 110 and the width W3 ofthe bottom frame 131 may be identical to or different from those of FIG.4, respectively. For instance, an internal angle θ3 between the sidewallframes 132 of a lead frame 130B is 60° Each sidewall frame 132 can beinclined at an angle of 30° with respect to the axis perpendicular tothe bottom frame 131. As the internal angle θ3 between the sidewallframes 132 of the lead frame 130B is increased, an interval D3(D3>D2>D1) between the sidewall frames 132 can be further widened.

FIGS. 7 to 10 are views showing lead frames modified according to thirdto sixth example embodiments.

Referring to FIG. 7, the lead frame 130C comprises the bottom frame 131and sidewall frames 132 bent from the bottom frame 131 at a right angle.In such a case, a width W4 of the bottom frame 131 and an interval D4between the sidewall frames 132 are 420 μm, and a cavity depth H4 of thelead frame 130C is 300 μm to 450 μm.

Referring to FIG. 8, the lead frame 130D comprises the bottom frame 131and one sidewall frame 132 inclined at an angle θ4 of 15° with respectto the axis perpendicular to the bottom frame 131. In such a case, acavity depth H5 of the lead frame 130D is 338 μm to 386 μm and aninterval D5 between the sidewall frames 132 is 600 μm to 626 μm. Forinstance, a width W5 of the bottom frame 131 is 420 μm.

Referring FIG. 9, the lead frame 130E comprises the bottom frame 131 andone sidewall frame 132 inclined at an angle θ5 of 30° with respect tothe axis perpendicular to the bottom frame 131. In such a case, a cavitydepth H6 of the lead frame 130E is 303 μm to 346 μm and an interval D6between the sidewall frames 132 is 770 μm to 850 μm. A width W6 of thebottom frame 131 is about 420 μm to 450 μm.

Referring to FIG. 10, the lead frame 130F comprises the bottom frame 131and sidewall frames 132A inclined at a predetermined angle with respectto the axis perpendicular to the bottom frame 131 while being bent witha predetermined curvature. In detail, the sidewall frames 132A areinclined at the predetermined angle and have a hemispherical shape toefficiently reflect light.

According to the lead frames as described above, when one sidewall frame132 has an inclination angle of 15° to 30° with respect to the bottomframe, the cavity depth is 250 μm to 700 μm, and the interval betweenthe sidewall frames 600 μm to 850 μm, the highest efficiency isobtained. Further, the lead frame, which has high reflective metal or isplated with high reflective metal material, has a reflectivity of 95% ormore, and has improved thermal resistance and thermal characteristics.Further, the inclined sidewall frame can improve the light intensity atthe center area.

FIG. 11 is a graph showing an angle of the lead frame as a function oflight intensity before and after the plating in the LED package of FIG.4, and FIG. 12 is a graph showing an angle of the lead frame as afunction of light velocity (or light amount) before and after theplating in the LED package of FIG. 4. The box plot shown in FIGS. 11 and12 is obtained using a blue LED having a specification of the same lightintensity and the same light velocity. Further, the intensity of lightand the velocity of light are measured using the same measurementspecimen.

Referring to FIGS. 11 and 12, in the LED package of FIG. 4, theintensities of light of first to fifth LED packages #1 to #5 aremeasured by changing the internal angle θ1 of the lead frame. The first,second, third and fifth LED packages #1, #2, #3 and #5 comprise a leadframe, which is subject to Ag-plating after the bending and punchingprocesses (see A). The fourth LED package #4 comprises a lead frame,which is subject to Ag-plating before the bending and punching processes(see B).

Further, the internal angles of the lead frames of the first to fifthLED packages #1 to #5 are 0°, 30°, 45°, 55°, and 55°, respectively.

FIG. 11 is a graph showing the angle of the lead frame as a function ofthe light intensity of the LED package, and Table 1 below shows theresult.

TABLE 1 Lv(mcd) #1 #2 #3 #4 #5 AVG 138.9 197.0 202.2 166.5 216.3 MIN114.0 177.9 168.1 143.4 190.8 MAX 154.1 215.4 221.5 183.1 243.6

As shown in FIG. 11 and Table 1, the difference of 1 cd (=1000 mcd) isgenerated according to the angle of the lead frame, after the plating A,and before the plating B. The second LED package #2 has an internalangle greater than that of the first LED package #1 by 30°, and has alight intensity increased by 41.8%. The third LED package #3 has aninternal angle greater than that of the second LED package #2 by 15°,and has a light intensity increased by 2.6%. Further, the fifth LEDpackage #5 has an internal angle greater than that of the third LEDpackage #3 by 10°, and has a light intensity increased by 7.0%.

FIG. 12 is a graph showing the angle of the lead frame as a function ofthe lumen of the LED package, and Table 2 below shows the result.

TABLE 2 Lm #1 #2 #3 #4 #5 AVG 0.389 0.482 0.495 0.431 0.503 MIN 0.3600.410 0.440 0.400 0.460 MAX 0.420 0.510 0.520 0.460 0.540

As shown in FIG. 12 and Table 2, the difference of lumen is generatedaccording to the angle of the lead frame, after the plating A, andbefore the plating B. The second, third and fifth LED packages have alight velocity increased by 24%, 26.7% (=24%+2.7%) and 28.2%(=24%+2.7%+1.5%) when the internal angle of the lead frame is increasedby 30°, 45°, and 55°, respectively.

Referring to FIGS. 11 and 12, the fourth LED package #4 has thepre-plated lead frame and the fifth LED package #5 has the post-platedlead frame. At this time, the fourth and fifth LED packages #4 and #5have the same internal angles. However, since the lead frame of thefourth LED package #4 is subject to Ag-plating before the bending andpunching processes, the Ag plating surface is damaged when bending thelead frame. Thus, the optical efficiency deteriorates.

Accordingly, the LED package shows the optimal light intensity when thelead frame has an internal angle of 30° to 55°. Further, the postplating scheme exhibits optical efficiency higher than the pre-platingscheme. Furthermore, the surface of the lead frame is plated with highreflective metal or high reflective material, so that the lead frame hasa reflectivity of 95% or more, and improved thermal resistance andthermal characteristics. In addition, the light intensity at the centerarea can be improved by the inclined sidewall frames.

Such a LED package can be applied to an indication field, a displayfield and the like, and can be provided to a terminal together with adisplay device.

FIG. 13 is a perspective view showing a display device using the LEDpackage according to the embodiment.

Referring to FIG. 13, the display device 200 comprises a light emittingapparatus 104 comprising a plurality of LED packages 100, a reflectiveplate 201, a light guide plate 203, an optical sheet 205 and a displaypanel 207.

The light emitting apparatus 104 comprises the LED packages 100 mountedon a substrate 102. As shown in FIGS. 1 to 3, in the LED package 100, aplurality of lead frames have a structure in which the bottom frames areintegrally formed with the sidewall frames thereof while the sidewallframes are being bent from the bottom frames, or can be prepared in theform of the aforementioned example embodiments.

Such a light emitting apparatus 104 corresponds to at least one side ofthe light guide plate 203, and light emitted from the light emittingapparatus 104 is incident into a lateral side of the light guide plate203.

The light guide plate 203 guides the incident light over the whole areaof the display device 200 and then outputs the light as surface light.Further, a reflective pattern (not shown) can be formed at one side ofthe light guide plate 203.

The reflective plate 201 is disposed below the light guide plate 203 toreflect light leaked through the light guide plate 203.

The light emitted from the light guide plate 203 is irradiated onto thedisplay panel 207 through the optical sheet 205. The optical sheet 205comprises at least one of a diffusion sheet (not shown), a horizontalprism sheet (not shown) and a vertical prism sheet (not shown). Thediffusion sheet is disposed on the light guide plate 203 to diffuse theincident light. The horizontal and vertical prism sheets are disposed onthe diffusion sheet to guide the diffused light toward a display area.

The light emitting apparatus 104, the light guide plate 203 and theoptical sheet 205 can be defined as a light unit. The light unit maycomprise the reflective plate 201. Further, a part of the elements ofthe light unit can be received in a structure (not shown) such as a moldframe, a chassis structure or a metal bottom cover.

The display panel 207 serving as a liquid crystal panel comprises twotransparent substrates (not shown) and a liquid crystal, and can displayinformation by transmitted light and driving of the liquid crystal. Theembodiment is not limited to such a display panel 207. Further, adisplay panel can be disposed at both sides of the light guide plate203.

Such a display device 200 can be applied to a portable terminal such asa cell phone or a PMP, or a computer.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure.

INDUSTRIAL APPLICABILITY

The embodiment can reduce optical loss in a cavity of an LED package.

The embodiment can improve the light intensity at a center area in acavity of an LED package.

The embodiment can increase the amount of reflected light in a cavity ofan LED package by using a lead frame plated with reflective metal orreflective material.

The embodiment can improve thermal resistance and thermalcharacteristics of a lead frame of an LED package.

1. A light emitting diode package comprising: a package body having acavity; a light emitting diode mounted in the package body; and a leadframe disposed in the package body, the lead frame comprising a planesurface electrically coupled to the light emitting diode in the cavityof the package body, and at least two lateral sidewall surfacesextending from the plane surface in the same direction as light from thelight emitting diode emits, wherein the cavity of the package body hasan inner sidewall inclined from the plane surface of the lead frame,wherein the package body has a partition to split up the lead frame,wherein the plane surface of the lead frame is extended to the outersurface of the package body so as to function as an electrode, whereinthe height of the lateral sidewall surfaces is in the range of 250 μm to700 μm, and wherein the distance between the uppermost portions of thelateral sidewall surfaces is in the range of 420 μm to 850 μm.
 2. Thelight emitting diode package according to claim 1, wherein theinclination angle of the lateral sidewall surface with respect to theimaginary axis perpendicular to the plane surface of the lead frame isin the range of 15 to 30 degrees.
 3. The light emitting diode packageaccording to claim 1, wherein the shapes of the split lead frames in thecavity are different from each other.
 4. The light emitting diodepackage according to claim 1, wherein the inner surface of the lateralsidewall surfaces is exposed toward the cavity.
 5. The light emittingdiode package according to claim 1, wherein the lateral sidewallsurfaces are embedded in the inclined inner sidewall of the cavity.